1. Field of Invention
The invention is related to multi-layer flashing systems for masonry.
2. Description of the Related Art
Traditionally, a masonry cavity wall is constructed having an inner back-up wall made of concrete, masonry block, brick, wood or steel frame construction, and an outer veneer wall of brick, stone, block, stucco, or other masonry. The two walls are separated by an air space or cavity. The width of this cavity can be specified by building code or architectural design preference. The purpose of this type of design, two walls separated by a cavity, is to prevent water from reaching the interior of the building as well as for its insulation value. As water penetrates the outer wall or “wythe”, it collects and condenses on the inner face of the outer wall. It runs down this surface to a point where its downward flow is interrupted by a horizontal plane such as a window, door, shelf angle, lintel, or the base of the wall itself. At these points, the water is diverted out of the wall by the through-wall flashing and weep devices which are placed in such a manner as to maximize the evacuation of the water. Weep devices can be metal or plastic tubes, ropes, and other devices.
Ideally, the flashing is affixed to the back-up wall by any of several methods. One method is to insert the flashing into a horizontal joint, if the back-up wall is a masonry block wall. Another method is to insert the flashing into a reglet, which is a horizontal slot placed in a poured concrete back-up wall. Yet another method is to mechanically fasten the flashing to the backup wall with screws and a termination bar. A termination bar is a strip of metal or plastic with evenly spaced holes for screws designed to spread the load evenly across the width of the bar. This may be used on any kind of back-up wall.
The flashing runs down the face of the back-up wall to a horizontal ledge or shelf. Then it turns and runs horizontally out and through the brick veneer, forming a continuous sheet that guides any water out of the wall and prevents any water from reaching the interior of the building. This flashing was traditionally made of heavy gauge copper or lead sheet that required trained metal workers to install correctly. Laps and seams needed to be soldered, which is difficult to do properly and in a watertight fashion.
One solution to this problem is disclosed in U.S. Pat. No. 2,005,221, which is not admitted to being prior art by its inclusion in this Background section. In that patent, a copper flashing is provided with a waterproofed fabric adhered to it. However, it cannot wick water away because it is waterproof by definition.
Another problem that appears in through-wall flashing/cavity wall construction is that, as the wall is built, excess mortar from subsequent layers of brick falls into the cavity and blocks the weep openings or ropes, which can render these very important components of this system inoperable. One solution to this problem was disclosed in U.S. Pat. No. RE36,676, which is not admitted to being prior art by its inclusion in this Background section. The solution to place something in the cavity that would allow water to migrate through to the weeps, yet prevent mortar and debris from clogging these openings. Other solutions, like using pea-stone gravel or a plastic mesh unit, are still in use today.
These cavity filling devices, both gravel and plastic, have deficiencies. The gravel is heavy and difficult to transfer to higher levels of scaffolding, which leads to it being omitted. There are also claims that, because of its density in the cavity, it allows the mortar to fill up the cavity, thereby defeating the purpose. The plastic mesh products, commonly marketed under the MORTAR NET and MORTAR BREAK trademarks, are quite expensive, often costing more than the flashing itself.
This has led to the need for a product that eliminates the need for other products, is easy to install, and performs as well or better as other products which, when combined, serve the same purpose, that of allowing the free flow of water from a masonry wall cavity.